1. Field of the Invention
This invention relates to an optical brightener composition containing a novel color salt consisting of an anionic optical brightener component and a basic color component.
2. Description of the Prior Art
For the optical brightening of organic materials, up to the present time, it has often been proposed to use an optical brightener with a very small amount of a colored dye (mainly, dye of blue, violet or reddish violet type) so as to make clearer the brightening effect and to control finely the color tone of the brightening effect. The dye used herein should have a clear color from the intended use and many of such dyes are basic dyes. However, the basic dyes are hardly used in this field because of the disadvantage that the light fastness tance is low, and dyes having a relatively clear color tone are predominantly chosen from dyes of disperse type. Therefore, the clearness of color is not satisfied.